In the past a number of improved coolant systems for vehicle engines have been proposed, such as for automobiles, taxi cabs, trucks, buses and the like. Many prefer to utilize a permanent anti-freeze in their coolant systems on a year round basis, with any unecessary loss of coolant fluid representing a loss of money.
From time to time many radiators overheat, due for example to a build up of bugs on the radiator, sludge in the system, faulty thermostat or the like, so the utilization of a pressure relief arrangement in the radiator cap has been a must. In order to prevent the wasting of permanent anti-freeze, a large percentage of the vehicles on the road today are equipped with a plastic jug or reservoir located near the radiator and arranged to catch the coolant that flows out of an overheated radiator, or a radiator whose internal pressure has exceeded the force of the spring used in the cap. The pressure caps currently in use, in addition to permitting the release of fluid when the radiator has overheated, have an additional valve permitting the cooling system, when the engine has cooled and the pressure has dropped below atmospheric, to suck a substantial amount of the coolant back out of the plastic jug and into the radiator. Although these arrangements have been popular and advantageous in many respects, as a consequence of being continuously open to the atmosphere, they have many attendant disadvantages.
For example, a large amount of oxidation takes place in the coolant system since a substantial quantity of air exists in the coolant system when the engine is not running, and there is considerable opportunity for oxidation of metallic parts to take place.
It was to overcome the disadvantages of these prior art systems that the present invention was created.